From: Remi Gacogne <rgacogne-github@coredump.fr>
Date: Mon, 28 Dec 2015 17:13:46 +0000 (+0100)
Subject: dnsdist: Fix truncateTC, it wasn't updating the response len anymore
X-Git-Tag: dnsdist-1.0.0-alpha2~135^2~2
X-Git-Url: https://granicus.if.org/sourcecode?a=commitdiff_plain;h=b50ee135121afcf9da9ad6deb0dd89c6a89d9cfd;p=pdns

dnsdist: Fix truncateTC, it wasn't updating the response len anymore

It was broken (still setting TC and fixing ancount, nscount and arcount
but not the response length) since the addition of ECS in
ca404e94c054df56d3f32abf66c643a1dec3b1b2, shame on me.
---

diff --git a/pdns/dnsdist.cc b/pdns/dnsdist.cc
index 50a3146f2..43835eafa 100644
--- a/pdns/dnsdist.cc
+++ b/pdns/dnsdist.cc
@@ -113,7 +113,7 @@ int g_tcpSendTimeout{2};
 
 bool g_truncateTC{1};
 bool g_fixupCase{0};
-static void truncateTC(const char* packet, unsigned int* len)
+static void truncateTC(const char* packet, uint16_t* len)
 try
 {
   unsigned int consumed;
@@ -153,24 +153,25 @@ void* responderThread(std::shared_ptr<DownstreamState> state)
 #else
   char packet[4096];
 #endif
+  static_assert(sizeof(packet) <= UINT16_MAX, "Packet size should fit in a uint16_t");
   const uint16_t rdMask = 1 << FLAGS_RD_OFFSET;
   const uint16_t cdMask = 1 << FLAGS_CD_OFFSET;
   const uint16_t restoreFlagsMask = UINT16_MAX & ~(rdMask | cdMask);
   vector<uint8_t> rewrittenResponse;
   
   struct dnsheader* dh = (struct dnsheader*)packet;
-  int len;
   for(;;) {
-    len = recv(state->fd, packet, sizeof(packet), 0);
+    ssize_t got = recv(state->fd, packet, sizeof(packet), 0);
     char * response = packet;
-    size_t responseLen = len;
 #ifdef HAVE_DNSCRYPT
     uint16_t responseSize = sizeof(packet);
 #endif
 
-    if(len < (signed)sizeof(dnsheader))
+    if (got < (ssize_t) sizeof(dnsheader))
       continue;
 
+    size_t responseLen = (size_t) got;
+
     if(dh->id >= state->idStates.size())
       continue;
 
@@ -188,7 +189,7 @@ void* responderThread(std::shared_ptr<DownstreamState> state)
     }
 
     if(dh->tc && g_truncateTC) {
-      truncateTC(packet, (unsigned int*)&len);
+      truncateTC(packet, (uint16_t*) &responseLen);
     }
     uint16_t * flags = getFlagsFromDNSHeader(dh);
     uint16_t origFlags = ids->origFlags;
@@ -270,7 +271,7 @@ void* responderThread(std::shared_ptr<DownstreamState> state)
       struct timespec ts;
       clock_gettime(CLOCK_MONOTONIC, &ts);
       std::lock_guard<std::mutex> lock(g_rings.respMutex);
-      g_rings.respRing.push_back({ts, ids->origRemote, ids->qname, ids->qtype, (unsigned int)udiff, (unsigned int)len, *dh});
+      g_rings.respRing.push_back({ts, ids->origRemote, ids->qname, ids->qtype, (unsigned int)udiff, (unsigned int)got, *dh});
     }
     if(dh->rcode == RCode::ServFail)
       g_stats.servfailResponses++;